Build a simple GUI that runs full Blender in the background?
Sounds like you're trying to re-invent the wheel.

I'd imagine you might use Python for your GUI
to remain consistent with Blender scripting.  

I'd look into PySide.
It's an open-source Python wrapper for the Qt lib.  

PySide can access OpenGL via PySide.QtOpenGL calls,
so you'd have a way to view your model that way.  

Then you'd most likely use a subprocess call to Blender
on the commandline for your final render.  

If you need to access bpy and all those features,
you could compile Blender as it's own Python module:
https://wiki.blender.org/index.php/User:Ideasman42/BlenderAsPyModule

You might look into the Blender 101 Project first.
https://code.blender.org/2016/12/the-blender-101-project-and-you

It might do what you're trying to accomplish.  

Contributing to that might be an easier way
for everyone to enjoy using Blender, even beginners.